I switched back from Visual Studio Code to vi (I tire of switching from keyboard to mouse). As my memory is not very good, here is my cheat-sheet for using :Termdebug
Starting a debug session: Termdebug [executable_name]
Navigating the 3 windows: CTRL + w and then j or k.
Set / remove a breakpoint: :Break :Clear
Step / Next: s or n
Run / Continue: run or c